Patent literature 1 discloses a storage subsystem including a first controller for controlling multiple drive units connected via multiple first switch devices, and a second controller for controlling the multiple drive units connected via multiple second switch devices associated with the multiple first switch devices, wherein the storage subsystem also includes a connection path that mutually connects the multiple first switch devices and the corresponding multiple second switch devices.
According further to the storage subsystem disclosed in patent literature 1, when the storage subsystem detects occurrence of a failure, it identifies the failure section in the connection path, and changes the connection configuration of the switch device so as to circumvent the failure section.
In other words, switch devices connected in a daisy chain mode are mutually connected between pairs having a redundant configuration, and when failure occurs, the connection configuration is rearranged so as to circumvent the section in which failure has occurred.
Further, patent literature 2 discloses coupling the pairs having a redundant configuration of switch devices coupled in a daisy chain mode in different orders.
As described, according to the conventional art, the two paths connected to an expander controller having a redundant configuration within a drive box composed of the drive unit and the expander controller are both connected in a daisy chain mode to the expander controllers in the subsequently arranged drive box.